1. Technical Field of the Invention
This invention relates to cutting bits or inserts for cutting work especially turning wherein the insert is detachably held in a tool holder of a lathe or similar machining apparatus.
2. Description of the Prior Art
Within the technical field is known a cutting bit insert which adjacent to the cutting edge presents a recess, down into which the middle portion of the chip is pressed during the machining operation. The side portions of the insert are kept in a somewhat higher plane in order to give the chip a lateral bending so that it will have less width than it has just upon leaving the cutting edge and thereby becomes narrower than the groove cut. The laterally bent chip can then roll itself and form a coil, which is narrower than the turned groove and does not causes damage to the machined surfaces or the like.
Within this field, it is also known to arrange, remote from the cutting edge of any tool, a chip breaker, that is a protruding portion which will be engaged by the cut chip in order to be guided away abruptly. This results in a breaking of the chip preventing it from forming continuous coils, spirals or spools which in turn might cause tool damages or damage to the work piece and machined surfaces. However, in this arrangement the chip is subjected to deformation during the breaking off process which increases its lateral width and tends to cause congestion of chips and poor surface finish on the side surfaces of the groove.
One essential aspect of this invention is to provide a new cutting insert that causes lateral bending of the chip and also causes it to break thereby producing short chips having less width than the groove cut. Such chips being easily removed from the groove without tendency to adhere to the sides of the groove, the tool or the like.